Graphics displays are widely used for displaying image data, which can include still image and/or video (moving image) data. A graphics display generally includes a plurality of rows and columns of pixels. Color graphics displays may include a plurality of rows and columns of red, green and blue (RGB) pixels. The design and operation of graphic displays, which will also be referred to herein simply as “displays”, are well known to those having skill in the art and need not be described further herein.
It is also known to provide display driver chips (integrated circuits) that can provide controllers, drivers, Random Access Memory (RAM) and/or other components that may be used to drive a display. The display driver chip may obtain data from a processor, such as an application processor and/or a microprocessor, and may store and output this data in a manner which is appropriate to drive a display. The overall design and operation of display driver chips also are well known to those having skill in the art and need not be described in detail herein. A display driver chip also may be referred to as a “graphics controller chip.”
Many devices that include a display provide an On-Screen Display (OSD) function, wherein image data and other information are independently displayed. The other information, referred to herein as “OSD data”, may relate to setup information, programming information, menu information, user messages, and/or other information that may be displayed on the display, independent of the image data that is displayed thereon. For example, FIGS. 1A and 1B illustrate a display wherein image data 110 is displayed on all of the rows and columns of the display and wherein OSD data 120 is independently displayed on the display. As shown in FIGS. 1A and 1B, the OSD data 120 may be blended with the image data 110. Moreover, although FIGS. 1A and 1B illustrate OSD data 120 at the bottom of the image data 110, the OSD data may be placed at any portion(s) of the image data. Multiple OSD data regions also may be provided. The design and use of OSD data are well known to those having skill in the art, and need not be described further herein.
FIG. 2 is a block diagram of a conventional display driver chip for displaying image data and/or OSD data on a display having a plurality of rows of pixels. In FIG. 2, the image data may be provided in the format of RGB data. However, other conventional formats of providing image data may be used for color displays, and RGB data may not be used for monochrome displays. As shown in FIG. 2, a conventional display driver chip 200 may be used for displaying image data and/or OSD data on a display 220 having a plurality of rows and columns of pixels. The display driver chip 200 includes an OSD data circuit 202, also referred to as an OSD memory, for storing OSD data, an image data circuit 204, also referred to as an image data memory, for storing the image data, an α-blending circuit 206 and a multiplexer (Mux) 208.
Still referring to FIG. 2, the image data circuit 204 receives image data, such as RGB data, from a processing circuit 230. In some displays, the processing circuit 230 may include a microprocessor 232 and an application processor 234. The image data circuit 204 may receive image data from the microprocessor 232 for still images, and from an application processor 234 for moving images (video), and stores the received image data in a memory in the image data circuit 204. The image data circuit 204 reads the image data stored in the memory row-by-row, and outputs the row to the α-blending circuit 206 and the Mux 208.
The OSD data circuit 202 receives OSD data from the processing circuit 230 and, in some embodiments, from the microprocessor 232 of the processing circuit 230, and stores the received OSD data in a memory in the OSD data circuit 202. The OSD data circuit 202 reads the OSD stored in the memory row-by-row, and outputs the data to the α-blending circuit 206.
The α-blending circuit 206 performs the operations of blending the image data and the OSD data in the OSD region, to blend, for example, 0%, 50% or 100% of the image data along with the OSD data, and thereby provide an unblended image or a blended image with various degrees of blending with the OSD data. Finally, the Mux 208 selects the image data and/or the α-blended data from the α-blending block 206, in response to a display control signal 236 from the processing block 230 and, in some cases, from the microprocessor 232, to thereby generate source data 222 to drive the display 220.
FIG. 3A is a more detailed block diagram of an image data circuit 204 of FIG. 2. In particular, as shown in FIG. 3A, the image data circuit 204 may be responsive to the microprocessor 232 for still image data and to the application processor 234 for moving picture data. The image data circuit 204 includes a display memory circuit 302 that is configured and sized so as to store therein an entire display image, for example, 132×176, 320×240 or 640×230 pixels of image data and an image line circuit 304, which reads the image data stored in the display memory circuit, line-by-line, and outputs this data to the α-blending circuit 206 and the Mux 208 line-by-line.
FIG. 3B is a block diagram of a conventional OSD data circuit 202. As shown in FIG. 3B, the OSD data circuit 202 includes an OSD memory circuit 312 that is configured to store the entire OSD data, for example 132×40, 320×40 or 640×80 of OSD data, and an OSD line circuit 314, which reads the OSD data stored in the OSD memory circuit 312 line-by-line and outputs the OSD data to the α-blending block 206.
An example of a display driver chip that includes OSD data circuitry thereon is described in the “Preliminary Specification for the Renesas HD66784, 262, 144-color, 176×320 dot Graphics Controller Driver for TFT LCD with Main/Sub Panel Simultaneous Drive”, by Renesas, Revision 0.2, Jul. 14, 2003. More specifically, Page 8 of this Preliminary Specification illustrates a block diagram of the driver and Page 96 illustrates a “base image area” and multiple “OSD image areas” in HD66784 RAM data.
Graphics displays may be increasingly used in small and/or portable devices such as wireless terminals, including cellular telephones, and/or in portable devices such as palmtop computers, wherein space may be at a premium and wherein it may be desirable to reduce power consumption. Even in larger and/or non-portable devices, it may be desirable to conserve space and/or power in the display driver.